public  class Example4_8 {
  public static void main(String args[]) {
     Circle circle = new Circle();
     circle.setRadius(10);
     Circular circular = new Circular();
     System.out.println("circle的引用:"+circle);	
     System.out.println("圆锥的bottom的引用:"+circular.bottom);
     circular.setHeight(5);	
     circular.setBottom(circle);
     System.out.println("circle的引用:"+circle);
     System.out.println("圆锥的bottom的引用:"+circular.bottom);
     System.out.println("圆锥的体积:"+circular.getVolme());
     System.out.println("修改circle的半径，bonttom的半径同样变化");
     circle.setRadius(20);
     System.out.println("bottom的半径:"+circular.getBottomRadius());
     System.out.println("重新创建circle,circle的引用将发生变化");
     circle = new Circle();
     System.out.println("circle的引用:"+circle);
     System.out.println("但是不影响circular的bottom的引用");
     System.out.println("圆锥的bottom的引用:"+circular.bottom);
  }
}

